An abstract sphere of infinite radius which serves as the imaginary backdrop for celestial objects, and of which the visible sky is one hemisphere.
the figure of the universe as an imaginary sphere whose center is the Earth
The sky which appears to an observer on the Earth as a dome in which celestial bodies are visible; the firmament.
The upper atmosphere occupied by clouds, flying birds, etc.
The place above the Earth where God or other deities live; heaven.